1. Technical Field
The present invention relates to a high pressure discharge lamp lighting device and a projector including the same, and more specifically, to a technique for preventing flicker.
2. Related Art
In the related art, for example, the following method is used in a high pressure discharge lamp lighting device used for a light source of a projector in order to stabilize the discharge arc in a high pressure discharge lamp (hereinafter, referred as a lamp): when an AC lamp current is supplied to a high pressure discharge lamp to turn on the high pressure discharge lamp, a current pulse having a period obtained by dividing half the period of the lamp current by a predetermined value is generated, the polarity of the current pulse becomes identical to the polarity of the lamp current, and a latter part of the half period of the current pulse is superposed on the lamp current (for example, JP-T-10-501919 (see claims and FIG. 4).
In the related art, the current pulse is superposed on the AC lamp current in synchronization with a latter part of the half period of the AC lamp current. Therefore, temperature increases in the electrodes in the lamp, and a discharge arc stably occurs, which prevents flicker. When the lamp is used as, for example, a light source of a projector, the brightness on a screen increases for a time corresponding to the superposition of the current pulse on the lamp current, which is an adverse effect. Since the current pulse is synchronously superposed on the lamp current, a partially bright portion is fixed at a predetermined position on the screen, which causes problems that the brightness on the screen is not uniform and a stripe occurs on the display screen.